I have never really considered the selection of router bits that are designed to produce locking joints. I recently came across a router bit that will cut a 45 degree angle and a locking tongue.
A single bit will cut both sides of the joint and does not require to be altered between cuts. Cut the first piece horizontally and the second vertically. The vertical cut can be tricky and dangerous. Depending on the length of the stock you may need a fence extension or a tennoning jig for your router table.
The vertical piece needs to be kept perpendicular to the router table and flush to the fence. Any wobble in cut will ruin the joint.
The profile the bit cuts provides a good amount of gluing surface and the locking tongues keep the miter joint together.
